Registering is an option that provides the benefit of syncing your locations, favorites, cameras and telescopes with the server. It uses one of your email accounts as validation so that no one else can claim to be you. Since you are not actually logging on to the server you will need to register each client/browser you will be using the app on. Your registered email at Tonight's Targets will not be used for marketing nor will it be sold. Please read the Privacy Policy and Contact Information page Privacy Policy